Performance evaluation of single channel virtual-circuit MAC protocols for MANETs

In this paper, we develop and evaluate models for estimating various performance metrics for unicast traffic using a single frequency channel virtual-circuit Medium Access Control (MAC) protocol in mobile wireless ad-hoc networks. Time is divided into periodic frames with a portion reserved for control traffic and the rest divided into timeslots for data traffic. In order to avoid interference between neighboring links, the virtual-circuit MAC protocol uses a set of reservation rules to assign timeslots to links. One such virtual-circuit MAC protocol is the hard scheduling mode of the reservation based Unifying Slot Assignment Protocol (USAP) with the number of frequency channels in a frame set to one. USAP uses a set of generic reservation rules to avoid interference between neighboring links. We model the performance of a single frequency channel virtual-circuit MAC protocol using reduced load loss network models that couple the physical, MAC, and routing layers effects. The blocking probability of a call at a particular link is calculated by considering cliques of neighboring interfering links that cannot transmit simultaneously. These neighboring interfering links and the conflict graph are calculated using the virtual-circuit reservation rules. We compare our results with simulation and show good match for large networks across various offered loads.